Philadelphia University
Faculty of Information Technology
Lecturer
: Dr. M. Maouche
Coordinator
: Dr M. Maouche
Internal Examiner : Prof.Dr. M. Mahafzah
Examination Paper
Department of Computer Science
Course Name: Computer Design and Organization (750233)
Section: 1
Second Exam
First Semester
Academic Year: 2014/15
Date: January, 4h, 2015
Time: 50 minutes
Information for Candidates
1.This examination paper contains 4 questions, totaling 22 marks.
2.The marks for parts of questions are shown in round brackets.
Advice to Candidates
1. You should write your answers precisely, clearly and to the point .
I. Basic Notions
Objectives. The aim of the question in this part is to evaluate the required minimal student
knowledge and skills. Answers in the pass category represent the minimum acceptable standard.
Question1: (8 marks)
1. Name three different types of buses. (2 marks)
2. Explain the difference between memory-mapped I/O and instruction-based
I/O. (2 marks)
3. Name four different types of Interrupts. ( 2 marks)
4. Name two different types of Control Unit. (2 marks)
II. Familiar Problems Solving
Objectives. The aim of the question in this part is to evaluate that the student has some basic
knowledge of the key aspects of the lecture material and can attempt to solve familiar
problems.
Question2: (4 marks)
How many bits are required to address a 1Mx 8 main memory if
a) Main memory is byte-addressable
b) Main memory is word-addressable
Question3 : (6 marks)
A digital computer has a memory unit with 24 bits per word. The instruction set
consists of 150 different operations. All instructions have an operation code part
(opcode) and an address part (allowing for only one address). Each instruction is
stored in one word of memory.
a) How many bits are needed for the opcode? (2 marks)
b) How many bits are left for the address part of the instruction? (2 marks)
c) What is the maximum allowable size for memory. (2 marks)
III. Unfamiliar Problems Solving
Objectives. The aim of the question in this part is to evaluate that the student has some basic
knowledge of the key aspects of the lecture material and can attempt to solve unfamiliar
problems.
Question4 : (4 marks)
Suppose we add the following instruction to MARIE’s ISA: IncSZ Operand
This instruction increments the value with effective address “Operand,” and if this
newly incremented value is equal to 0, the program counter is incremented by 1.
Basically, we are incrementing the operand, and if this new value is equal to 0, we
skip the next instruction.
Show how this instruction would be written using Register Transfer
Notation.